PS command and multithread

Hi,
I have a multi thread program, let' s called it ABC.
when I do ' ps -e -o pcpu -o comm |grep ABC '
it shows 4 processes which is correct (since it's multithread)
however the value of pcpu (which is percent cpu) does not change over time.
for comparison I use top and the cpu usage changes every second
Is this something to do with the fact that my machine is hyperthread
How can I capture the cpu usage using ps or anyother tool?
thanks
-Yuneus